The present invention relates to a diagnostic apparatus of a coolant temperature sensor, a diagnostic apparatus of a cooling apparatus and method, and particularly to those applied to an engine of a vehicle.
In Japanese Patent Application Laid-open No. H10-73047, there is disclosed that a counter for measuring the time after an engine started is provided, and that when the measured time exceeds a predetermined value, if the coolant temperature detected by a water temperature sensor does not reach a judgment value, it is judged that a trouble of output drop occurs in the water temperature sensor.